Organic photoconductive materials which have been developed as photosensitive materials or hole-transporting materials have many advantages including low cost, variety of processability, and non-polluting nature. Many compounds have been proposed. For example, materials such as oxadiazole derivatives (see, for example, patent document 1), oxazole derivatives (see, for example, patent document 2), hydrazone derivatives (see, for example, patent document 3), triarylpyrazoline derivatives (see, for example, patent documents 4 and 5), arylamine derivatives (see, for example, patent documents 6 and 7), and stilbene derivatives (see, for example, patent documents 8 and 9) have been disclosed.
Of these, starburst materials such as 4,4′,4″-tris[N,N-(1-naphthyl)phenylamino]triphenylamine (1-TNATA) and 4,4′,4″-tris[N,N-(m-tolyl)phenylamino]triphenylamine (MTDATA) and biphenyl type arylamine derivatives such as 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPD) and 4,4′-bis[N-(m-tolyl)-N-phenylamino]biphenyl (TPD) are frequently used as hole-transporting or hole-injecting materials (see, for example, non-patent documents 1 and 2).
Furthermore, arylamine compounds employing a fluorene framework as a partial structure have also been proposed (see, for example, patent documents 10 and 11).
Moreover, an organic electroluminescent material having the same benzofluorene framework as in this patent has also been proposed (see, for example, patent document 12). However, this patent document includes no statement concerning a compound having an amino group directly bonded to the benzofluorenyl group. In addition, although patent document 12 includes a statement to the effect that a polymeric material having benzofluorenyl groups is especially useful as a luminescent material, there is no statement therein to the effect that the polymeric material is useful as a hole-transporting material and a hole-injecting material.    Patent Document 1: U.S. Pat. No. 3,189,447 (Claims)    Patent Document 2: U.S. Pat. No. 3,257,203 (Claims)    Patent Document 3: JP-A-54-59143 (Claims)    Patent Document 4: JP-A-51-93224 (Claims)    Patent Document 5: JP-A-55-108667 (Claims)    Patent Document 6: JP-A-55-144250 (Claims)    Patent Document 7: JP-A-56-119132 (Claims)    Patent Document 8: JP-A-58-190953 (Claims)    Patent Document 9: JP-A-59-195658 (Claims)    Patent Document 10: JP-A-11-35532 (Claims)    Patent Document 11: JP-A-10-95972 (Claims)    Patent Document 12: International Publication No. 2004/61048 Pamphlet (Claims)Non-Patent Document 1: Advanced Materials, (Germany), 1998, Vol. 10, No. 14, pp. 1108-1112 (FIG. 1, Table 1)Non-Patent Document 2: Journal of Luminescence, (Holland), 1997, 72-74, pp. 985-991 (FIG. 1)